(RHSA-2015:0043) Important: kernel security and bug fix update

The kernel packages contain the Linux kernel, the core of any Linux
operating system.

• A flaw was found in the way the Linux kernel’s SCTP implementation
  handled malformed or duplicate Address Configuration Change Chunks
  (ASCONF). A remote attacker could use either of these flaws to crash the
  system. (CVE-2014-3673, CVE-2014-3687, Important)

• A flaw was found in the way the Linux kernel’s SCTP implementation
  handled the association’s output queue. A remote attacker could send
  specially crafted packets that would cause the system to use an excessive
  amount of memory, leading to a denial of service. (CVE-2014-3688,
  Important)

The CVE-2014-3673 issue was discovered by Liu Wei of Red Hat.

This update also fixes the following bugs:

• When the Baseboard Management Controller (BMC) was reset, the settings
  for the ipmi_watchdog driver were not restored correctly causing error 80
  to be returned. With this update, Intelligent Platform Management Interface
  (IPMI) is reset as expected in the described situation, and the error is no
  longer returned. (BZ#1109268)

• Under certain conditions, XFS log flushes could exceed the kernel thread
  stack size. As a consequence, a kernel panic occurred on systems using XFS
  file systems. This update provides a patch that moves this code path to a
  work queue, and therefore the stack overflow no longer occurs. (BZ#1154086)

• Due to a race condition, an attempt to unmount an XFS file system using
  the umount command could fail, causing the system to become unresponsive.
  The underlying source code has been modified to fix this bug, and the
  system no longer hangs in the described situation. (BZ#1158320)

• Previously, the printk_ratelimited() function printed messages which were
  supposed to be suppressed, and failed to print messages that were supposed
  to be printed. This was caused by the incorrect usage of the __ratelimit()
  function. This bug has been fixed with this update, and now
  printk_ratelimit() behaves as expected. (BZ#1169401)

All kernel users are advised to upgrade to these updated packages, which
contain backported patches to correct these issues. The system must be
rebooted for this update to take effect.